water from the Ihell, in order that it may fwim the more 
readily,; then throwing back the two foremoft arms, it 
difplays between them a membrane of wonderful te¬ 
nuity, which adts as a fail, while with the remaining 
arms it rows itfelf along; the tail in the middle adting 
as a helm to direct its courfe ; and thus purfues its voy¬ 
age like a little {hip; and if alarmed by any appea¬ 
rance of danger, takes in the water and defcends.” 
We mult be careful not to confound this fhell, which 
is the real and proper Nautilus, with the chambered 
or pearly Nautilus, which belongs to a very diftindt 
genus. The Argonauta Argo is found of various fizes, 
from one to fix or eight inches in length, or even 
larger. It is a native both of the Mediterranean and 
Indian feas. 
